Vane damping

ABSTRACT

Damping of compressor or turbine vanes in the supporting shroud is accomplished by surrounding one end of the vane with a damping material of the steel wool or felt metal type held in contact with the shroud in which the vane is loosely supported.

United States Patent 11 1 1111 3,778,184

Wood 1 Dec. 11, 1973 1 VANE DAMPING 3,519,222 7/1970 Davis 415/1743,071,346 1/1963 Broffit r 415/137 [751 Glasmnbury, 3,556,735 11/1963Epelman 60/297 Conn.

[73] Ass1gnee: United Aircraft Corporation, East Primary Examiner camonR cmyle Hartford, Conn.

Assistant Examiner-Louis J. Casaregola [22] Filed: June 22, 1972Att0rr7ey-Charles A. Warren [21] Appl. No.: 265,413

[52] 11.8. C1. 415/174, 415/191 [57] ABSTRACT W [511 E Fold 11/08 Fold1/02 Fold 9/00 Damping of compressor or turbine vanes in the sup- [58]Fleld 01 Search 415/174, 219, 136, porting Shroud is accomplished bysurrounding one 415/137 191; 416/190 500 end of the vane with a dampingmaterial of the steel wool or felt metal type held in contact with theshroud [56] References cued in which the vane is loosely supported. 1

UNITED STATES PATENTS 2,952,442 9/1960 Warnken 415/174 4 Claims, 2Drawing Figures 'PAIENIEnnm 1 ma Z? M XX VANE DAMPING BACKGROUND OF THEINVENTION This invention relates to damping the vanes in a compressor orturbine.

Damping has been accomplished by positioning a thermoplastic orthermosetting material between the end of the vane and the supportingshroud or around the vane externally of the shroud with the dampingmaterial functioning as a bond between the vane and the shroud. Heat maybe required in placing the material in the desired position around thevane ends and in some cases heat may be essential in curing thethermosetting material.

A feature of the present invention is a damping structure which requiresno heating of the device or the material. Another feature is a dampingstructure in which the effectiveness of the damping may be controlled bymore or less compressing the damping material prior to or duringinstallation. Another feature is the damping of vane vibration by amaterial of the felt metal, steel wool or braided or knit wire type.

According to the present invention the row of vanes are secured to theinner shroud and extend loosely through slots in the outer shroud withthe vane ends surrounded by damping material of the felt metal, steelwool or braided or knit wire type thus forming a damper for vanevibration. This material is different in structure and function fromother damping material in that it is a resilient fibrous material with asignificant porosity. This material is in contact with the sides of thevane adjacent to the ends of the vanes and may also be in contact withthe outer ends of each of the vanes if so desired. The damping materialis positioned between the shroud and a surrounding cover plate thatholds it in position to accomplish the desired damping.

Other features and advantages will be apparent from the specificationand claims and from the accompanying drawings which illustrate anembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial sectionalviewthrough a vane assembly showing the damping materials therein.damping FIG. 2 is a fragmentary sectional view along the line 2-2 ofFIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A row of vanes 2 only one ofwhich is shown in FIG. I are supported at their inner ends by an innershroud ring 4 the vanes being brazed or welded or otherwise secured inslots 6 in this inner shroud ring.

Each of the vanes extends outwardly through a slot 8 in the outer shroudring 10 and the outer end of the vane extends beyond the outer surfaceof the shroud ring as shown. The shroud ring 10 is preferably somewhatU-shaped in cross section having outwardly projecting flanges l2 and 14with laterally projecting flange rings 16 and 18 thereon. The outeredges of the rings 16 and 1 8 may have attachment flanges 20 and 22 forsecuring the adjacent stages of compressor vanes thereto.

The outer end of each vane is received in a porous compressible pad 24of felt metal, stainless steel wool, braided wire or knit wire whichencircles the vane end tightly and extends over the tip of the vane. Asheet metal cover 26 attached as by rivets 28 to the shroud ring holdsthe damping material in place and may serve to preload the materialagainst the vanes and acts as a seal. The compartment defined betweenthe shroud ring 10 and the cover 26 is a fixed dimension within whichthe damping pad is compressed. When the vane vibrates energy isdissipated at the contact surface of the vane and damper and internallywithin the damper. This arrangement requires no structural restraint onthe outer end of the vane with respect to the shroud and serveseffectively to reduce vibratory stress levels.

The damping material may extend over a plurality of vanes or there maybe a separate damping pad for each of the vane ends. In either event thecover plate 26 holds the pads in position and may be utilized to apply apredetermined load on the damping material thereby to control theeffective damping action. It may be desirable to form the pad with anotch 30, F IG. 2, to receive the end of the vane although this :may beunnecessary in many instances depending on the length that the vaneprojects beyond the shroud ring and the amount of damping pressure thatis to be applied to the end of the vane by the damping material.

A form of pad that has proved to be satisfactory for this purpose is aporous stainless steel single filament wire pad since it will beeffective for a longer period of time at the hot end of a multistageaxial flow compressor. Other wire pad structures in which the wires arefeathered together are equally usable. It will be understood that theamount that the pad is compressed thereby reducing the porosity willdetermine the effectiveness of the damping action on the vane end. Itshould be noted that no particular preparation is necessary for the vaneend since the wire pad is not attached to the vane positively in anyway. It may be desirable to provide notches 32 and 34 at the leading andtrailing edges of the vane at its outerend since this arrangement willserve to provide a broader surface for damping vibrations chordwise ofthe vane.

I claim:

1. A turbine vane assembly including a row of turbine vanes extending ina generally radial direction about an axis,

an inner shroud to which the inner ends of the vanes are secured,

an outer shroud having openings therein through which the outer ends ofthe vanes project,

a porous wire mesh fabric forming a compressible pad surrounding andreceiving therein the outer end of each vane on the outer side of theouter shroud for damping purposes, and

a band surrounding said outer shroud and overlying the outer ends of thevanes, said hand holding the wire mesh fabric in position, said bandbeing se cured to said outer shroud.

2. A turbine vane assembly as in claim 1 in which said wire meash fabricis an open work material made up of a plurality of metallic wiresfeathered together to form a compressible mass.

3. A turbine vane assembly as in claim 1 in which said wire mesh extendsaround substantially the entire periphery of the outer shroud.

4. A turbine vane assembly as in claim 1 in wire mesh is in contact withboth the sides and the end of each of the vanes.

I t 4 Q I which said I mg? l a v UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTION Patent No 3,778,184 Dated December 11, 1973 n flslDonaldH. Wood It is certified that error appears in theabove-identified patentand that said Letters Batent are hereby corrected as shown below:

Column 1, line 32, delete "may" line 32, delete "be" and insert--desirably-- lines 44-45, delete "damping" second 7 occurrence 7 Column2, line 30, change "feathered' to --felted-- line 32, delete "thereb yreducing the porosity" line 58, change Y'meas h" to -n1esh-- line 59, 1change "feathered" to --:Eelted-- Signed and sealed this 21st day of May1971+.

(SEAL) Attest: I

'0. MARSHALL DAM Commissioner of Patents EQWAEPW QL Attesting Officer

1. A turbine vane assembly including a row of turbine vanes extending ina generally radial direction about an axis, an inner shroud to which theinner ends of the vanes are secured, an outer shroud having openingstherein through which the outer ends of the vanes project, a porous wiremesh fabric forming a compressible pad surrounding and receiving thereinthe outer end of each vane on the outer side of the outer shroud fordamping purposes, and a band surrounding said outer shroud and overlyingthe outer ends of the vanes, said band holding the wire mesh fabric inposition, said band being secured to said outer shroud.
 2. A turbinevane assembly as in claim 1 in which said wire meash fabric is an openwork material made up of a plurality of metallic wires featheredtogether to form a compressible mass.
 3. A turbine vane assembly as inclaim 1 in which said wire mesh extends around substantially the entireperiphery of the outer shroud.
 4. A turbine vane assembly as in claim 1in which said wire mesh is in contact with both the sides and the end ofeach of the vanes.